Hot isostatic pressing of metallic or ceramic powders, so called HIP or HIPPING is a commonly used manufacturing process for various articles. In the HIP manufacturing process a capsule which defines the shape of the article is filled with a metal or ceramic powder of desired composition. The capsule is evacuated, sealed and thereafter subjected to increased temperature and pressure whereby the powder is densified into a compact body.
Powder based articles may in certain applications be subjected to conditions that varies along the article. Alternatively, may the design and geometry of the article be such that different parts or portions are more exposed to the surrounding environment than others. For example, the load or the pressure may be larger on one portion of the article than on another portion of the article. The wear, for example abrasive wear, that an article is subjected to, may also be larger on one portion than on another portion of the article. Due to increased wear, for example, on certain portions of the article, the article may wear out or break earlier than expected from the overall wear. The non-limiting terms “varying physical influence” and “increased physical influence” are used hereinafter to include all types of effects from the surrounding environment on the article, and that the effect may be more pronounced on one portion of the article than another, respectively.
Attempts have been made to reinforce powder based articles by increasing the dimensions of the article in the portions where it is subjected to increased physical load. However, due to dimension requirements this is not always possible.
Other attempts to reinforce powder based articles include flame coating as described in EP 0543353 A1 and JP 3125076 A1. However, these methods have had limited success. The microstructure of the article degrades due to the heat from the coating process. It has further proven difficult to reach certain portions of the articles with the flame coating tools. The thickness of the applied layer, as well as the choice of materials that can be used, is also limited in the known methods.